
Answer:
a. genotype; bb
Explanation:
Given that;
The allele for brown eye color is dominant (B) Â to the allele for blue eye color (b)
and Topanga’s mother has blue eyes
Definitely the traits of Topanga’s mother is recessive for blue traits = bb
Her father has brown eyes = Bb (since B is dominant over b) therefore, the b allele is not expressed.
So if Bb crosses with bb; we have:
             B            b
b            Bb            bb
b            Bb            bb
∴ Since Topanga has blue eyes, it is expressed by the genotype bb because bb is a recessive genotype expressing the blue eye color.